Whales claim record for longest mammal migration

EACH winter, humpback whales travel from the Antarctic to the northern tropics to find warm water in which to raise their young. The migration is the longest documented for any mammal.

Kristin Rasmussen of Cascadia Research Collective in Olympia, Washington, and her colleagues photographed the tails of humpbacks wintering off the Caribbean coast of Costa Rica. From their individual tail patterns they identified seven of the same animals after they had returned to the Antarctic. One mother and calf made the 8300-kilometre trip in 161 days (Biology Letters, DOI: 10.1098/rsbl.2007.0067).

Using satellite data, the team also recorded sea-surface temperatures for the sites where humpbacks spent the winter. "Wintering areas occur where waters with temperatures between 21 °C and 28 °C are found," says Rasmussen. This supports the idea that the long migration saves the whales energy in the end.